Superbill

In order to fight counterfeiting, particularly superbills (near-perfect fake $100 bills), the U.S. Mint changed the $100 bill, the favorite of counterfeiters, first.

Medical offices may store superbills for record-keeping purposes, in case they need to be referenced in the future. A good example may be tracking a procedure that did not get posted because it was missed on the superbill at the time charges were entered.